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Chapter: Medicine and surgery: Nervous system

Dementia - Disorders of consciousness and memory

A syndrome of acquired cognitive impairment, with progressive global loss of cognitive function in the context of normal arousal. - Definition, Incidence, Aetiology, Pathophysiology, Clinical features, Complications, Investigations, Management, Prognosis.

Dementia

 

Definition

 

A syndrome of acquired cognitive impairment, with progressive global loss of cognitive function in the context of normal arousal.

 

Incidence

 

1% of those aged 65–74 years, 10% of those over 75 and 25% of those over 85 years.

 

Aetiology

 

There are numerous causes of dementia, including

 

·        Alzheimer’s disease (most common >60%).

 

·        multiinfarct dementia caused by multiple small infarctions, decline may be step-wise (20%). dementia with Lewy bodies (5%).

 

·        fronto-temporal dementias (10%) such as cortical atrophy.

 

·        alcohol.

 

·        hydrocephalus, subdural haematoma, previous head injuries (punch-drunk syndrome).

 

·        infections such as syphilis, HIV or prion diseases (Creutzfeld Jacob disease).

 

Clinical features

 

See also under specific causes of dementia. Patients may have impairment of the following cognitive functions:

 

·        Learning and retaining new information, e.g. remem-bering recent events.

 

·        Impaired reasoning, judgement.

 

·        Ability to carry out complex tasks, e.g. managing household finances.

 

·        Language skills, e.g. word finding.

·        Spatial memory and orientation (e.g. wandering, getting lost).

 

·        Personality and behaviour, loss of social skills, some-times with aggression or sexual disinhibition.

 

Apathy and/or depression are common, there may be disturbances of sleep, confusion of day & night, with nocturnal restlessness and wandering. Auditory or visual hallucinations and delusions are particularly common in dementia with Lewy bodies. Other neurological signs such as hemiparesis, seizures tend to occur very late in dementia.

 

Generally, in the early stages, the patient is aware of a loss of their memory and may become very frustrated and anxious. It may at first be attributed to ‘old age’. They lose the ability to function in daily life gradually, and in later stages they become more apathetic, with little spontaneous effort and therefore require full personal care such as feeding, washing, dressing and toiletting.

 

A collateral history from a relative or close carer who has known the patient for a long time is essential. The carer is often the one most emotionally affected by the changes wrought by dementia.

 

 

Investigations

 

These are to exclude any treatable causes of chronic confusion.

 

·        Bloods: FBC, U&Es, calcium, LFTs, Vit B12, thyroid function tests, blood glucose, syphilis serology.

 

·        Chest X-ray.

 

·        CT or MRI brain to look for cortical atrophy and exclude hydrocephalus, subdural haematoma or a space-occupying lesion such as a cerebral metastasis. There may be specific changes of specific dementias.

 

Management

 

The specific management strategies are covered under specific causes but general treatment includes the following:

 

·        Multidisciplinary assessment.

 

·        Family support responding to the changing needs of carers.

 

·        Home care/day care/respite care/residential care/ hospital care.

 

·        Behavioural problems may respond to phenothiazines or atypical neuroleptics.

·        Antidepressants may improve functional level in those with low mood.

 

·        Psychological therapy.

 

·        For mild to moderate Alzheimer’s dementia, multi-infarct dementia and dementia with Lewy bodies, cholinesterase inhibitors such as donepezil have been shown to be of benefit, in delaying the need for nursing home care.

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Medicine and surgery: Nervous system : Dementia - Disorders of consciousness and memory |

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